function setBackLogTime (mss) {
  if (!mss) return '00:00';
  const days = Math.floor(mss / (1000 * 60 * 60 * 24));
  const hours = Math.floor((mss % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
  const minutes = Math.floor((mss % (1000 * 60 * 60)) / (1000 * 60));
  const seconds = Math.floor((mss % (1000 * 60)) / 1000);
  const res = setDateTimePrefix(minutes) + ':' + setDateTimePrefix(seconds);
  if (days) {
    return  days + res
  } else if (hours) {
    return setDateTimePrefix(hours) + ':' + res
  } else {
    return res
  }
}
export function setDateTimePrefix (dateTime) {
  return dateTime < 10 ? `0${dateTime}` : `${dateTime}`;
}
function secondsFormat( s ) {
  let day = Math.floor( s/ (24*3600) ); // Math.floor()向下取整 
  let hour = Math.floor( (s - day*24*3600) / 3600); 
  let minute = Math.floor( (s - day*24*3600 - hour*3600) /60 ); 
  let second = s - day*24*3600 - hour*3600 - minute*60; 
  return day  + hour + minute + second; 
}
export { setBackLogTime, secondsFormat }